Drinking flask



FIG. 1 is a top, front and right side perspective view of a drinking flask showing my new design;

FIG. 2 is a bottom, rear and right side perspective view thereof;

FIG. 3 is a front elevation view thereof, the rear elevation being a mirror image thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is an exploded view of the drinking flask shown in FIG. 1. 

The ornamental design for a drinking flask, as shown and described. 